Re: [PATCH RFC v2 2/8] bus: mhi: host: add new interfaces to handle MHI channels directly

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Jan 31, 2024 at 03:39:26PM +0800, Baochen Qiang wrote:
> 
> 
> On 1/31/2024 2:19 AM, Manivannan Sadhasivam wrote:
> > On Mon, Nov 27, 2023 at 06:20:16PM +0200, Kalle Valo wrote:
> > > From: Baochen Qiang <quic_bqiang@quicinc.com>
> > > 
> > > When using mhi_power_down_no_destroy() MHI hosts need to unprepare MHI channels
> > > by themselves.  Similarly, MHI stack will also not create new MHI device since
> > > old devices were not destroyed, so MHI hosts need to prepare channels as well.
> > > Hence add these two interfaces to make that possible.
> > > 
> > > Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
> > > 
> > > Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
> > > Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
> > > ---
> > >   drivers/bus/mhi/host/main.c | 107 ++++++++++++++++++++++++++++++++++++
> > >   include/linux/mhi.h         |  20 ++++++-
> > >   2 files changed, 126 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> > > index d80975f4bba8..3f677fc628ad 100644
> > > --- a/drivers/bus/mhi/host/main.c
> > > +++ b/drivers/bus/mhi/host/main.c
> > > @@ -1669,6 +1669,58 @@ int mhi_prepare_for_transfer_autoqueue(struct mhi_device *mhi_dev)
> > >   }
> > >   EXPORT_SYMBOL_GPL(mhi_prepare_for_transfer_autoqueue);
> > > +static int ____mhi_prepare_for_transfer(struct device *dev, void *data)
> > 
> > "__mhi_prepare_all_for_transfer"
> 
> This is to prepare one single child device, I don't think a name like
> __mhi_prepare_all_for_transfer (with 'all' inside) make sense, right?
> How about changing to "mhi_prepare_dev_for_transfer" or
> "mhi_prepare_single_for_transfer"?
> 

I think most of the checks in this function can be moved inside
mhi_prepare_for_transfer() API. With that you can just reuse the API without
adding a new helper.

For autoqueue channels, you can add another API
mhi_prepare_all_for_transfer_autoqueue() just like
mhi_prepare_for_transfer_autoqueue() to maintain uniformity.

- Mani

> > 
> > > +{
> > > +	struct mhi_device *mhi_dev;
> > > +	struct mhi_chan *ul_chan, *dl_chan;
> > > +	enum mhi_ee_type ee = MHI_EE_MAX;
> > 
> > Reverse Xmas order, please.
> > 
> > > +
> > > +	if (dev->bus != &mhi_bus_type)
> > > +		return 0;
> > > +
> > > +	mhi_dev = to_mhi_device(dev);
> > > +
> > > +	/* Only prepare virtual devices that are attached to bus */
> > 
> > "Only prepare virtual devices for the channels". Here and below.
> > 
> > > +	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
> > > +		return 0;
> > > +
> > > +	/* There are cases where there is no MHI client driver matches
> > > +	 * this device, we are not allowed to do prepare for it.
> > > +	 */
> > 
> > Use the preferred style for comment:
> > 
> > 	/*
> > 	 * ...
> > 	 */
> > 
> > > +	if (!mhi_dev->id)
> > > +		return 0;
> > > +
> > > +	ul_chan = mhi_dev->ul_chan;
> > > +	dl_chan = mhi_dev->dl_chan;
> > > +
> > > +	/*
> > > +	 * If execution environment is specified, remove only those devices that
> > > +	 * started in them based on ee_mask for the channels as we move on to a
> > > +	 * different execution environment
> > > +	 */
> > > +	if (data)
> > > +		ee = *(enum mhi_ee_type *)data;
> > > +
> > > +	if (ul_chan && ee != MHI_EE_MAX && !(ul_chan->ee_mask & BIT(ee)))
> > > +		return 0;
> > > +
> > > +
> > 
> > Remove extra newline.
> > 
> > > +	if (dl_chan && ee != MHI_EE_MAX && !(dl_chan->ee_mask & BIT(ee)))
> > > +		return 0;
> > > +
> > > +	if (dl_chan->pre_alloc)
> > > +		return mhi_prepare_for_transfer_autoqueue(mhi_dev);
> > > +	else
> > > +		return mhi_prepare_for_transfer(mhi_dev);
> > > +}
> > > +
> > > +int mhi_prepare_all_for_transfer(struct mhi_controller *mhi_cntrl)
> > > +{
> > > +	return device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL,
> > > +				     ____mhi_prepare_for_transfer);
> > > +}
> > > +EXPORT_SYMBOL_GPL(mhi_prepare_all_for_transfer);
> > > +
> > >   void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev)
> > >   {
> > >   	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> > > @@ -1684,3 +1736,58 @@ void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev)
> > >   	}
> > >   }
> > >   EXPORT_SYMBOL_GPL(mhi_unprepare_from_transfer);
> > > +
> > > +static int ____mhi_unprepare_from_transfer(struct device *dev, void *data)
> > 
> > __mhi_unprepare_all_from_transfer
> 
> same as above.
> 
> > 
> > > +{
> > > +	struct mhi_device *mhi_dev;
> > > +	struct mhi_chan *ul_chan, *dl_chan;
> > > +	enum mhi_ee_type ee = MHI_EE_MAX;
> > > +
> > > +	if (dev->bus != &mhi_bus_type)
> > > +		return 0;
> > > +
> > > +	mhi_dev = to_mhi_device(dev);
> > > +
> > > +	/* Only unprepare virtual devices that are attached to bus */
> > > +	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
> > > +		return 0;
> > > +
> > > +	/* There are cases where there is no MHI client driver matches
> > > +	 * this device, so it is not probed or prepared, no need to
> > > +	 * do unprepare for it.
> > > +	 */
> > > +	if (!mhi_dev->id)
> > > +		return 0;
> > > +
> > > +	ul_chan = mhi_dev->ul_chan;
> > > +	dl_chan = mhi_dev->dl_chan;
> > > +
> > > +	/*
> > > +	 * If execution environment is specified, remove only those devices that
> > > +	 * started in them based on ee_mask for the channels as we move on to a
> > > +	 * different execution environment
> > > +	 */
> > > +	if (data)
> > > +		ee = *(enum mhi_ee_type *)data;
> > > +
> > > +	if (ul_chan) {
> > > +		if (ee != MHI_EE_MAX && !(ul_chan->ee_mask & BIT(ee)))
> > > +			return 0;
> > > +	}
> > > +
> > > +	if (dl_chan) {
> > > +		if (ee != MHI_EE_MAX && !(dl_chan->ee_mask & BIT(ee)))
> > > +			return 0;
> > > +	}
> > > +
> > > +	mhi_unprepare_from_transfer(mhi_dev);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +int mhi_unprepare_all_from_transfer(struct mhi_controller *mhi_cntrl)
> > > +{
> > > +	return device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL,
> > > +				     ____mhi_unprepare_from_transfer);
> > > +}
> > > +EXPORT_SYMBOL_GPL(mhi_unprepare_all_from_transfer);
> > > diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> > > index ae092bc8b97e..dcf62a57056a 100644
> > > --- a/include/linux/mhi.h
> > > +++ b/include/linux/mhi.h
> > > @@ -668,7 +668,7 @@ static inline void mhi_power_down(struct mhi_controller *mhi_cntrl, bool gracefu
> > >    * destroy struct devices. This is a variant for mhi_power_down() and is a
> > >    * workaround to make it possible to use mhi_power_up() in a resume
> > >    * handler. When using this variant the caller must also call
> > > - * mhi_prepare_all_for_transfer_autoqueue() and
> > > + * mhi_prepare_all_for_transfer() and
> > 
> > This change belongs to previous patch.
> > 
> > >    * mhi_unprepare_all_from_transfer().
> > >    *
> > >    * @mhi_cntrl: MHI controller
> > > @@ -842,4 +842,22 @@ int mhi_queue_skb(struct mhi_device *mhi_dev, enum dma_data_direction dir,
> > >    */
> > >   bool mhi_queue_is_full(struct mhi_device *mhi_dev, enum dma_data_direction dir);
> > > +/**
> > > + * mhi_prepare_all_for_transfer - if you are using
> > > + * mhi_power_down_no_destroy() variant this needs to be called after
> > > + * calling mhi_power_up().
> > 
> > Add info about what this API does also.
> > 
> > > + *
> > > + * @mhi_cntrl: MHI controller
> > > + */
> > > +int mhi_prepare_all_for_transfer(struct mhi_controller *mhi_cntrl);
> > > +
> > > +/**
> > > + * mhi_unprepare_all_from_transfer - if you are using
> > > + * mhi_power_down_no_destroy() variant this function needs to be called
> > > + * before calling mhi_power_down_no_destroy().
> > 
> > Same as above.
> > 
> > - Mani
> > 
> > > + *
> > > + * @mhi_cntrl: MHI controller
> > > + */
> > > +int mhi_unprepare_all_from_transfer(struct mhi_controller *mhi_cntrl);
> > > +
> > >   #endif /* _MHI_H_ */
> > > -- 
> > > 2.39.2
> > > 
> > > 
> > 

-- 
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